Why All-Nighters Don’t Work

by Leah Burrows

Want to ace that big presentation to the boss tomorrow? Here’s a tip: Put down the coffee, and hit the sack.

Scientists have long known that sleep, memory and learning are deeply connected. Most animals, from flies to humans, experience memory problems when they are sleep-deprived, because sleep is critical in the conversion of short-term memory into long-term, a process known as memory consolidation.

But just how this process works has remained a slumbering mystery. Does the neuronal mechanism that promotes sleep also consolidate memory? Or are two distinct processes working together? In other words, are memory neurons actually putting us to sleep, or is memory consolidated during sleep because the brain is quiet, allowing memory neurons to go to work?

Research by neuroscience graduate students Paula Haynes and Bethany Christmann makes a case for the former. In a recent paper, Haynes and Christmann studied dorsal paired medial (DPM) neurons, well-known memory consolidators in fruit flies. They observed, for the first time, that when DPM neurons are activated, flies snoozed more. When deactivated, the flies kept buzzing.

Neuronal memory consolidators inhibit wakefulness as they convert short-term memory into long-term memory in a section of the fly brain called the mushroom body (similar to the memory-storing hippocampus in humans). As it turns out, the parts of the mushroom body responsible for memory and learning also help keep the fruit fly awake and on its game.

“It’s almost as if that section of the mushroom body is saying, ‘Hey, stay awake, and learn this,’” says Christmann. “Then, after a while, the DPM neurons start signaling to suppress that section, as if to say, ‘You’re going to need sleep if you want to remember this later.’”

Understanding how sleep and memory are connected in a simple system like the fruit fly can help scientists unravel the secrets of the human brain.

“Knowing that sleep and memory overlap in the fly brain allows researchers to narrow their search in humans,” Christmann says.

“Eventually, it could help us figure out how sleep or memory is affected when things go wrong, as in the case of insomnia or memory disorders.”